My Sound Dampening Enclosure for almost finished CNC Router

[Nealieboyee]

Hello All,
I thought I'd share my progress with my sound dampening enclosure I've been building for my CNC router.
When I started building my CNC, I knew I'd have to have some sort of enclosure, and with the neighbours that I have it would have to be pretty effective at cutting down the noise.

Enclosure is made of an MDF outer shell, then a 10mm gap, then the inside "panels", which are HEAVY.

Each panel is made up of the following layers. 12.5mm plasterboard, CLS timber frame filled with 50mm Rockwool sound insulation, 10mm carpet, 18mm MDF, 10mm carpet again (around the rim only this time, leaving a 10mm gap in the middle).

The completed panels are extremely heavy. After calculating based on the weight of a sheet of mdf and plasterboard, I'd have to say close to 45-50kg each. Thickness of each panel comes to around 110mm.

The only screws used on the panels was to make the CLS frame. All layers are glued together using either contact adhesive (for the carpet, mdf layers) or gripfill (for the plasterboard layers). I wanted to minimize the amount of vibration transference through screws and bolts by omitting them altogether.

Here are a few pics. I still have the front panel/Door to make tomorrow, and I'm still unsure how I will hinge it. Also to do are ports for cables and baffles for fans/airflow.

https://farm8.staticflickr.com/7912/33443935768_88218d4304_k.jpg

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[Greeny]

Thanks for sharing, that should do a pretty good job.

It would be interesting if you could let us know how much noise it cuts out when you are up and running.

Cheers

[routercnc]

Looks good. Box in box is a classic solution and with minimum structural connection between them should work well. Note that the surrounding inner box will amplify the sound inside which makes the outer box work harder. The carpet will help with absorption but only at fairly high frequencies. If you can line the ceiling with something thicker and fluffier it will help.

Services in and out are best done with long trunking lined with absorption, so don’t just go straight through each panel but start at the top (say) of the inner and bend 90 deg down to run down the void, with a rubber coupling in the middle, then bend 90 and go out of the outer panels. So the upper trunking is mounted to the inner panel and the lower trunking is mounted to the outer panel. You can get rectangular trunking which might fit depending on the gap size.

Good work

[A_Camera]

I think the idea of sound proofing is good, but I also think that the table is not going to be strong and rigid enough for a CNC and that the rubber wheels will make the whole machine too shaky. My CNC is made in a similar way but out of 45x90 aluminium extrusions and originally I also had similar wheels, but after some use I realized that the shake is just too violent when the CNC was in use and that it also affected maximum speed and accuracy, so I changed the solution. The table is now lowered onto the floor, and the wheels are only used when I want to move it around, which is not happening that often. Also, the noise level actually dropped after the change, even though the aluminium extrusion feet is not touching the floor, resting directly on some wooden blocks between the floor and the machine feet. My advice it that you think about this before it is too late, so you don't have to make too many changes later.

[Nealieboyee]

Looks good. Box in box is a classic solution and with minimum structural connection between them should work well. Note that the surrounding inner box will amplify the sound inside which makes the outer box work harder. The carpet will help with absorption but only at fairly high frequencies. If you can line the ceiling with something thicker and fluffier it will help.

Services in and out are best done with long trunking lined with absorption, so don’t just go straight through each panel but start at the top (say) of the inner and bend 90 deg down to run down the void, with a rubber coupling in the middle, then bend 90 and go out of the outer panels. So the upper trunking is mounted to the inner panel and the lower trunking is mounted to the outer panel. You can get rectangular trunking which might fit depending on the gap size.

Good work

Thanks very much for your input. Loved the new video of part one of the pedal car build. Very nice. I wish I could be as neat, clean, and precise as you are. Trunking might be a problem as the gap between inner and outer boxes is only 10mm. But I'm working on baffle boxes to run air and cables in and out.


I think the idea of sound proofing is good, but I also think that the table is not going to be strong and rigid enough for a CNC and that the rubber wheels will make the whole machine too shaky. My CNC is made in a similar way but out of 45x90 aluminium extrusions and originally I also had similar wheels, but after some use I realized that the shake is just too violent when the CNC was in use and that it also affected maximum speed and accuracy, so I changed the solution. The table is now lowered onto the floor, and the wheels are only used when I want to move it around, which is not happening that often. Also, the noise level actually dropped after the change, even though the aluminium extrusion feet is not touching the floor, resting directly on some wooden blocks between the floor and the machine feet. My advice it that you think about this before it is too late, so you don't have to make too many changes later.

Thanks man. I removed all four castors and the table/bench now sits on two planks on the floor. I had to use a car jack to lift it and unbolt the castors haha. Was scary.

First sound test completed. This is with a wood router placed inside the box and the cable simply hanging out the bottom of the door ( squished by the latches). Router is at max rpm. The front panel/door has a single polycarb window 4mm thick on the inside. I will be putting one outside too. I did a small test with my phone playing music inside the box, and the sound leakage was definitely coming mostly through the polycarb, so with a second sheet in place, I expect the sound level to drop further. Listen for the drop in sound level once the third clip is latched.

Honestly, I can't believe how quiet it is. My hand saw makes more noise on each stroke than this. I can still hear ambient noise while this is running. I suppose the true test will be when it starts cutting material like aluminium.


https://youtu.be/xpBMiklj3gA

[Nealieboyee]

Sound Test 2
I've added the outside polycarb window to create a double glazed effect.

https://youtu.be/VTtwhtDYiG8

[Kitwn]

What are you doing about cooling inside the box? My first CNC machine was built into a closed box but it got far too hot inside. I burnt out the motor of my Makita C700 router by installing it in a temporary installation with insufficient cooling air circulation so can say from experience that this matters. I'd also be concerned about the build up of chips and the consequent fire risk if you have no dust extractor in there. I had some experience of that as well, it was why I finally decided to dissmantle the box.

I've just switched from using a brushed router (a Chinese clone of the same C700) to a 2.2kW water cooled brushless spindle on my CNC router and the drop in noise is amazing. Now it's the dust extractor that makes the most noise and there is no high pitched scream which could be heard for some distance outside my shed.

Kit

[Nealieboyee]

What are you doing about cooling inside the box? My first CNC machine was built into a closed box but it got far too hot inside. I burnt out the motor of my Makita C700 router by installing it in a temporary installation with insufficient cooling air circulation so can say from experience that this matters. I'd also be concerned about the build up of chips and the consequent fire risk if you have no dust extractor in there. I had some experience of that as well, it was why I finally decided to dissmantle the box.

I've just switched from using a brushed router (a Chinese clone of the same C700) to a 2.2kW water cooled brushless spindle on my CNC router and the drop in noise is amazing. Now it's the dust extractor that makes the most noise and there is no high pitched scream which could be heard for some distance outside my shed.

Kit

Thanks for your comments Kit.
I installed a baffle box and extraction fan pretty early on. It does a good job and motors barely get warm, though my jobs aren't much longer than around 20 mins.

As for the fire risk, I NEVER leave the shed when the CNC is powered up. If I have to go somewhere, I switch off and make sure EStop is engaged. I also have a fire extinguisher next to the machine.
I've been running the 2.2kw water cooled spindle from day one :). I still need a decent dust extraction system though. Working on it.